An encoding method includes, when a first code rate K/Nmax is less than or equal to a code rate threshold Rt, reading a first matrix from a preset code table based on a second matrix. The second matrix includes a matrix that is read from the preset code table and that corresponds to a maximum supported code length Nmax and Rt, where K is an integer and N is an integer. The method also includes reading K rows and (N−K) columns starting from a preset first location in the first matrix to obtain a third matrix. The method further includes adding a unit matrix with K rows and K columns to a left side of the third matrix to obtain a generator matrix of an (N, K) linear block code. K rows and (Nmax−Nmax×Rt) columns of the second matrix in a first direction are consistent with K rows and (Nmax−Nmax×Rt) columns of the first matrix in a second direction.